"My feet are firmly on the ground. And it's really humbling," Kasich said.

Kasich said the country needs to be united again, and his experience in Ohio shows he can do that.

"If you come to this state as a divider you will lose," he said. "This state in some ways was in that kind of a bad financial situation. I ran for governor, I figure if I get elected, there's nowhere to go but up. The same is true for America. What you do is you re-engineer things. You make things work better."

Kasich is in the bottom tier of the 16 current GOP candidates, but said he isn't daunted. He said radio host Hugh Hewitt recently asked him about his electability.

"I said who cares about electability, how about capability?" he said. "What if we elect somebody and they don't change anything? What's that going to do. We got to have somebody ready to go. We can all talk. Politicians, we're talkers. It's not about talkers, it's about doers."